1. Field
This disclosure relates to generating traffic for testing a network or network device.
2. Description of the Related Art
In many types of communications networks, each message to be sent is divided into portions of fixed or variable length. Each portion may be referred to as a packet, a frame, a cell, a datagram, a data unit, or other unit of information, all of which are referred to herein as packets.
Each packet contains a portion of an original message, commonly called the payload of the packet. The payload of a packet may contain data, or may contain voice or video information. The payload of a packet may also contain network management and control information. In addition, each packet contains identification and routing information, commonly called a packet header. The packets are sent individually over the network through multiple switches or nodes. The packets are reassembled into the message at a final destination using the information contained in the packet headers, before the message is delivered to a target device or end user. At the receiving end, the reassembled message is passed to the end user in a format compatible with the user's equipment.
Communications networks that transmit messages as packets are called packet switched networks. In order to test a packet switched network or a device included in a communications network, it is often desirable to generate network traffic having a data rate equal to the line rate or maximum possible data rate of the network communication path or device.
A series of packets originating from a single source and having a specific type of packet and a specific rate will be referred to herein as a “stream.” A source may be, for example, a port on a network interface. A source may support multiple outgoing streams simultaneously and concurrently, for example to accommodate multiple packet types or rates. “Simultaneously” means “at exactly the same time.” “Concurrently” means “within the same time.”
For the purpose of reporting network traffic data, the packets within a stream may be organized into flows, where a “flow” is any plurality of data units for which network traffic statistics are accumulated and reported. The data units in a given flow may be distinguished by a flow identifier contained in each data unit. The flow identifier may be, for example, an address, a port number, a tag, or some other field or combination of fields within each data unit.
A plurality of concurrent streams may be combined to form the output from a traffic generator, which will be referred to herein as “test traffic”. The streams within the traffic may be combined through interleaving. The interleaving may be balanced, unbalanced, and distributed among the represented streams. The data rate of the test traffic may be equal to the line rate of a network communication path over which the output is transmitted. Although the packets within a given stream may be transmitted at the line rate, the average data rate of each stream over time may be much lower, since a plurality of interleaved streams may share the data rate of the test traffic. To test a modern “triple play” network and network equipment, the test traffic may contain simulated data, audio, and video streams.
Throughout this description, elements appearing in block diagrams are assigned three-digit reference designators, where the most significant digit is the figure number and the two least significant digits are specific to the element. An element that is not described in conjunction with a block diagram may be presumed to have the same characteristics and function as a previously-described element having a reference designator with the same least significant digits.
In block diagrams, arrow-terminated lines may indicate data paths rather than signals. Each data path may be multiple bits in width. For example, each data path may consist of 4, 8, 16, 32, 64, or more parallel connections.